The present invention relates to a wet clutch system utilized as a starting clutch in a continuously variable transmission.
In hydraulically-actuated clutches employed for power transmission purposes, the actuation of the clutch is dependent upon the pressure of the hydraulic fluid acting on the engaging elements of the clutch. Where there is circulating fluid for cooling the frictional faces, the viscous drag resulting from oil flowing between the clutch plates when the clutch is in released position results in the problem that the clutch is not fully released. Thus, unwanted driving input to the transmission input shaft is created during disengagement of the clutch, with a brake being added to the output shaft with its resultant inefficiencies. Another possible solution to the viscous drag is the dumping or release of the oil flow to the clutch, but timing is critical for this arrangement.
Another problem resides in the centrifugal force of the rotating clutch which results in liquid pressure which may influence actuation of the clutch. Other problems include engine stalling during a rapid vehicle braking and smoothness of clutch engagement during acceleration. The present invention will in its various forms obviate the above enumerated problems.